September 13, 2011

Cool Reverberations, Angelic Echoes, and Horowitz’s Nail.

Why does music played in Boston’s Symphony Hall sound so much better than the music in San Francisco’s Davies Symphony Hall?

It is said that fish are unaware of the water. The fish, of course, were not consulted, but the point being made is that the mind-fishy or human-takes accustomed surroundings for granted. That is why music listeners rarely separate their perception of music from factors imposed on it by the acoustical environment in which the music is heard-the ambience that mediates between themselves and their music. 

Professional musicians, by contrast, have long been aware that the sound of music is partly a matter of architecture, and artists on tour constantly complain about having to adjust their playing to the acoustics of different halls. 

They are also aware that many pieces are written for a particular kind of acoustical setting. For example, Berlioz envisioned echoing cathedrals for his larger choral and orchestral works, while Mozart fares best in more intimate surroundings, reminiscent of the drawing rooms of his patrons. But the public, by and large, pays attention to such matters only after some spectacular acoustical fiasco, as in the case of Lincoln Center's notorious Philharmonic Hall. 

The hall had been ballyhooed by its promoters as the last word in acoustical finesse, but no sooner had Leonard Bernstein raised his baton at the festive inaugural concert, than it became apparent that the hall was an acoustical disaster. Because the hall lacked warmth and reverberance, the music sounded dry, harsh, and bloodless. The bass, in particular, was missing, and thus the music was robbed of that deep sonority which is the glory of a truly great orchestra. The New York Philharmonic, famed for its richly burnished timbres, sounded as if all the cellos and contra basses had gone on strike. You could see the players desperately digging their bows into the strings, but only a thin and anemic mewling was to be heard. Shaken and perplexed, the trustees of Lincoln Center called in George Szell, the late conductor of the Cleveland Orchestra. What, they asked, might be done to improve the hall? Szell's recommendation was specific: "Tear it down." 

For more than a dozen years one acoustical expert after another meddled with the hall, usually making matters worse. Finally it was decided to follow Szell's advice. Granted, they didn't tear down everything. The outer walls were left standing. It looked less embarrassing that way. But everything inside was rebuilt in under the guidance of Columbia University's eminent acoustician Dr. Cyril M. Harris. Avery Fisher, the hifi magnate, picked up most of the cost. Having made a fortune from music by selling equipment for its electronic reproduction, Fisher was, in a way, paying a debt of gratitude. Anyway, his generosity provided the New York Philharmonic with a fit place for playing music, and it seems only proper that the hall now bears his name. 

This curious history would be recalled in musical circles as a cautionary tale.  As events at Lincoln Center showed, concert-hall acoustics are erratic and unpredictable, and the result of a remodeling often eludes the most expert calculations. Nor is the sad experience at Lincoln Center unique. On the contrary, it is typical. As if to mock our era's facile pride in its technology, most concert halls built since World War II have turned out to be acoustical duds. Notable examples include the Royal Festival Hall, in London, where the sound was so severely flawed that eventually electronic devices had to be installed to simulate those sonic attributes-depth, warmth, and reverberance-that were missing from the natural character of the auditorium. Another instance of acute acoustical disappointment was the Louise M. Davies Symphony Hall, in San Francisco.  At its opening, its jinxed acoustics managed to reduce the powerful pianism of Rudolf Serkin to a mere tinkle.

On the whole, builders of concert halls seemed to do better in the past. A surprising number of halls built in the nineteenth century had outstanding acoustics.

"Horowitz's nail" was added to the stage at Carnegie Hall in the 1920s, when the young maestro determined that his piano sounded best throughout the hall from that spot.

Tragically, many of these splendid structures fell victim to air warfare (another dubious achievement of the last century), among them the great opera houses of Vienna, Dresden, and Munich; the Singakademie, in Berlin; and the Queen's Hall, in London. Fortunately, several survived to serve as models for our time, and it is among these that I count some my favorite places for listening to music: Vienna's Musikvereinssaal, Amsterdam's Concertgebouw, and Boston's Symphony Hall. 

I had my earliest encounters with great music at these halls, but I was too young to appreciate their warmth, intimacy, reverberant spaciousness and clear elucidation of sonic detail. 

The pairing of these attributes is rare. A hall can be reverberant, lending warmth and weight to the blended orchestral textures of Romantic composers from Schubert to Mahler; or it may have a spare, analytic sound, revealing more clearly the separate strands of the performers. In such a hall musicians never have to strain to achieve the volume necessary for a convincing orchestral climax. String players, in particular, do not have to dig in their bows to balance the loudness of the brass. As a consequence, the sound never gets harsh or strident. Sweetness and sonority are preserved even in the loudest passages, and singers never have to force the voice. 

The questions naturally arise, just what makes one concert hall better than another, and why do the old ones seem superior? Here are some of the answers that have emerged. 

The traditional way to evaluate concert halls was to measure their total reverberation time, that is, the time it takes for all the echoes in the hall to die down. As a rule, a hall with a long reverberation time-two seconds in the case of the Vienna Musikvereinssaal and the Amsterdam Concertgebouw-has a warmer and richer sound than halls with a shorter period, and many concert halls have a reverberation time of hardly more than one second. But in recent decades many additional criteria were discovered. Electronic instruments now enable acousticians to differentiate "early sound" (the sound reaching the listener within one fiftieth of a second after its onset) from reflections arriving later. The ratio of early to late sound is crucial, and if it differs only slightly from its optimum, the subjective sound impression suffers greatly. As Dr. Theodore J. Schultz, an eminent Boston acoustician explained it, "The early sound carries immediacy. It gives a feeling of closeness and presence. But it's like garlic in a dish. Just a bit too much overbalances everything else."

Acousticians also discovered why those older halls often sounded better than the new ones. Their elaborate decorations-plaster angels, curlicues, and caryatids-yield multiple reflection surfaces in a more or less random pattern, diffusing and mellowing the sound. Modern halls, by contrast, mostly favored clean architectural lines that return the echo as a single hard slap of sound. As a remedy, acousticians suspended plastic "clouds" from the ceiling of such spare interiors-free-form panels with undulant contours-to substitute for those outdated angels. 

Interpreting the results of their computer-aided measurements, modern acousticians think of sound in a concert hall as a fluid churned by a multitude of vortexes. Many overlapping factors enter into the overall pattern of the sound flow: the rate of fading of the various echoes, resonances induced by various shapes of architectural space, the absorptive and reflective properties of building materials, and the directional patterns of sound reflections-to name but a few. What complicates matters even more is that all these factors vary at different locations within the hall and in different segments of the musical frequency spectrum.

 Juggling all these factors is always a gamble, and many new built halls must be extensively modified (or "tuned," as their designers prefer to call it) after completion. Nor is there any agreement among leading acousticians about the most promising approach. 

Dr. Cyril M. Harris, the acoustics rescuer of Avery Fisher Hall and designer of the superb new Orchestra Hall in Minneapolis as well as the four fine halls in Washington's Kennedy Center, firmly believed in the traditional rectangular shape for an auditorium and regarded any deviation from this norm as an invitation to trouble. By contrast, Christopher Jaffe, the acoustician for notable successful concert halls in Denver and Mexico City, favors music in the round, with the orchestra surrounded by circular ranks of listeners. This shortens the average distance between players and listeners and thus contributes to a feeling of intimacy. He relies largely on adjustable reflecting panels within the auditorium to create the desired acoustical ambience.

Surprisingly, both of these seemingly contradictory approaches work. The decisive factors are the skill and aural sensitivity of the designer, which raises the question whether acoustics is a science or an art. According to Cyril Harris, it's a combination of both: "We do have science. But the job is too complex to be an exact science. When it comes to certain refinements, an acoustician has to use his judgment on the basis of experience. Then acoustics becomes an art."

And Abraham Melzer, an acoustical consultant of international renown answered: “It’s not just a matter of measurements, granted, technical considerations are basic.  But a feeling for the different kinds of musical sound-something like a painter’s feeling for color-is equally important.  That’s why acoustics can never be reduced to mathematical formulas.”

1 comment:

Charles said...

Hm, much food for thought.